SYNTHESIS AND DEGRADATION OF JUVENILE-HORMONE-III DURING THE FINAL 2 LARVAL STAGES OF FEMALE AND MALE CRICKETS, GRYLLUS-BIMACULATUS DEGEER (ENSIFERA, GRYLLIDAE)

The rates of synthesis of juvenile hormone In were determined in femal e and male penultimate and final larval instars of the Mediterranean f ield cricket, Gryllus bimaculatus, using an in vitro radiochemical ass ay, Throughout the penultimate larval stadium, mean rate of juvenile h ormone synthesis declines from about 4 pmol . hr(-1). pair corpora all ata (CA)(-1) on day 0 to less than 1 pmol . hr(-1)pair CA(-1) on day 5 , but increases again prior to the next larval moult (day 6). During t he first 24 hr of the final larval stadium, mean rates of juvenile hor mone synthesis are between 5-6 pmol . hr(-1). pair CA(-1) and thereaft er drop below 0.5 pmol . hr(-1). pair CA(-1) by day 4. Immediately fol lowing imaginal ecdysis, the corpora allata of virgin females synthesi ze juvenile hormone III at higher rates than those observed throughout the final larval instar, The accumulation of methyl farnesoate within the corpora allata parallels the rates of juvenile hormone III synthe sis, but at a lower level, Juvenile hormone III esterase activity in h emolymph, as measured in vitro, is moderate during the penultimate lar val stadium (ca. 200 pmol . hr(-1).mu l(-1)) and increases significant ly to a high level from day 2 to the end of the final larval stadium, There is no sexual dimorphism in timing or magnitude of juvenile hormo ne Dr synthesis and juvenile hormone III esterase activity, respective ly.